The Cube: No ordinary office block

There are very few streets named after architects in London (or anywhere, come to that). But now we have an addition to this select band. Tanner Lane might sound like a medieval alley in the City, but no: it’s the brand new street that loops around Renzo Piano’s Paddington Square. It immortalises Sir Henry Tanner (1849-1935), Office of Works architect of the rather fine but unlisted 1892 red brick and brown stone Royal Mail sorting office that was demolished to make way for it.

There was quite a preservation battle over that, headed by the Victorian Society and Save Britain’s Heritage, to no avail: no trace of Tanner is to be found here now other than the new street name. Instead you get a great big white cube of an office and retail building set between Brunel’s Paddington Station and the rambling St Mary’s Hospital complex. This is fortunately no ordinary spec office block, in that no Piano building is ever entirely ordinary. The 55m by 55m box is set high, 12m above datum, with two levels of retail and an underground station beneath.

The exterior of the 18-storey Paddington Square demonstrates the Renzo Piano Building Workshop’s (RPBW) love of precise detailing, the 75cm module of the facade with its slender slotted white vertical fins being much more finely-grained than the norm. It is designed to be visually solid from some angles (pale stuccoed walls are common round here), and glassy from others.

Narrow horizontal brises-soleil slice across the otherwise vertically organised cladding, while a stack of small balconies pops out to enliven the elevation on the south-eastern elevation towards Praed Street. At the north-western corner closest to the railway terminus, greater vertical emphasis is given by a pair of freestanding scenic lifts serving the big (415 covers) rooftop restaurant with its terrace. That is due to open in 2025.

The ‘cube’ is the central portion of a building which is organised classically into three sections: base, shaft and top-knot – though the top and bottom sections of the sandwich are inset rather than projecting. The full-height glass cladding is very necessary to light the floors in a building that is much deeper-plan than the norm, something emphasised by the fact that the rectangular core is placed off-centre, towards the north-east side. Maximum depth is 20m from wall to core rather than the standard 12m, with floor-to-ceiling heights of 2.9m. 

There are no atria, though deep notches are taken out of the corners. These allow a typical dematerialising Piano detail: the facade glazing projects slightly beyond the enclosed volume at these inset corners.  The developers have certainly taken a risk to maximise floorplate dimensions in this way but it seems to have paid off in this very well-connected location. Anchor tenant, investment fund manager Capital Group, has taken nine interlinked floors.

Externally the building with its exposed structural steelwork is perhaps as delicate as anything this bulky can be, and it gives as much as it can to the public realm on a tight site. RPBW project partner Joost Moolhuijzen likes to point out that the team  ‘kept its promises’ or even bettered them when it came to the streetscape and transport improvements. Its frame tapers inwards at the base to make space, primarily to carve out the wider and pedestrianised approach to the station that is as close to a ‘square’ as the plan allows. Previously this was a vehicle route descending behind a wall from Praed Street to the fourth span extension (1913-15) of Brunel’s original three-span train shed. At the top there was a rabbit-hole Bakerloo Line tube station entrance.  Now there is a large new Bakerloo foyer built into the base of the Piano building, right by the main station entrance into the fourth span at this corner.

There is a prequel to this story, and that is the ‘Paddington Pole’. As originally proposed by the Sellar Property Group, the developer behind Piano’s Shard at London Bridge, with its Singaporean-owned partner Great Western Developments (GWD), this was to be a 254m cylindrical residential 75-storey tower with lower buildings at its base in the Shard manner. That was presumably a ranging shot for the planners in this low-to-medium rise district. Predictable outrage resulted, the application was withdrawn, the artillery was recalibrated and the Pole was replaced with the Cube. The public realm and public transport enhancements were broadly the same in both designs.

The entrance lobby to the office floors starts above the retail podium. You arrive via an open-air bank of escalators sheltered by the building’s overhang and the mast-hung glass skirt that runs round it, doubling as pedestrian canopy and downdraught deflector. You move into a broad reception/lounge area leading to a café, gym and the double-height lift lobby. The atmosphere is touch-down clubbable in the way of such shared areas in big blocks now, pleasant enough but nothing special (separate interior designers were involved).

The bank of lifts in the tall lobby whizz you to your floor – in my case I got to see the sections that have yet to be fitted out and so inevitably resemble all other empty spec office blocks with their generic raised floors, vaster than usual in this case. Care has been taken with the ceilings, though, with no equipment projecting lower than the bottom flange of the girders spanning between the tubular steel columns spaced at  9m intervals.

This care extends to how the ceilings are seen from below. Although as usual tenants are given a largely free hand with their fit-outs, here a broad ceiling zone around the perimeter of each floor is sacrosanct so there is a uniform appearance from street level. Equally, the solar-control perforated blinds are contained within the double-wall cladding so those – which respond automatically to weather conditions – are also uniform all the way up.

The facade, moreover, has natural trickle ventilation within it, designed to reduce solar overheating. As a whole the block is sealed and air-conditioned, though a number of measures ranging from banks of PV panels on the roof to a large bike garage in the basement (pretty much standard now in London) are hoped to keep it to its BREEAM ‘Excellent’ target.

What most of us will experience is the base section. It’s a small retail mall down there, the usual selection of eateries and clothing chains, on the whole a cut above the generally more downmarket shops in the area.

Overall Paddington Square is a civilised, intelligently thought-out place. Pointless to argue whether it’s a better or worse piece of architecture than Tanner’s sorting office, given the huge leap in scale. There’s no denying that an important chunk of the area’s working history has gone for a spec development, but this one is better than most in making a cut-above building work pretty hard for the public.

In numbers

Overall development cost (2020 prices) £825m 
Tube station redevelopment £65m 
Total area 40,000 m2 
Office area 32,500 m2 
Public realm 5,463 m2 
Retail units 33 
Storeys high 18 
Rooftop restaurant 1